Migrate to new flycheck checker definition macro.

A recent commit to flycheck removed the checker definition macro kibit
is currently using, effectively breaking compatibility.

Please refer to: 5aef21f515fb5166df35304da3871cab7ea4af46

These changes support the new checker's definition syntax, without
trying to maintain backwards compatibility.
Backwards compatibility.
Merge pull request #5 from julienfantin/master

Migrate to new flycheck checker definition macro.